This book is based on research conducted to investigate whether interactivity yields a learning effect when used appropriately in e-Learning Systems, and whether this effect enhances learning. There is no doubt interactivity is vital in learning. This statement is emphasized to such an extent that it is claimed that students with higher levels of interaction will obtain more positive and higher levels of achievement. However, little scientific evidence can be found to support this relationship.The importance of this book is based on the fact that it provides evidence of the impact of interactivity on e-Learning Systems considering the three main agents of an educational activity: the learner, the teacher and the environment.In addition, the concept of feedback as a key element in any interactive mechanism for enhancing learning is well documented in several studies throughout this book.Three empirical studies are presented that investigated interactivity within the educational triangle. These three studies were conducted based on the framework of positivism and action research paradigms. The first study, entitled Interactive Pedagogical Feedback , gathers evidence for how highly interactive pedagogically designed formative feedback enhances students’ memory and understanding.The second study, entitled Interactive Audio Feedback , examines whether the speed enhancements of oral feedback improve the conditions for the production of the lecturer’s feedback and the quality of the feedback delivered to the students.The final study, Interactive Texting Feedback , takes a pedagogical approach to provide formative feedback to a student audience using mobile text messages, and determines whether Interactive Texting Feedback enhances the learning experience within the e-Learning environment.The information contained in the book is useful for academics and institutions to improve their teaching and the efficiency of their learning delivery mechanisms, and will guide the design of instructional content. It will also be of utility to other researchers and those in roles that require an understanding of interactivity.